The long-term goal of this research program is to develop an optical magnetometer for use in fetal magnetocardiography (fMCG) and fetal magnetoencephalography (fMEG) systems. We believe that the proposed magnetometer represents the first viable alternative to SQUID magnetometers; thus, the potential impact of the research on the field of biomagnetism is enormous. We have developed a novel, small-volume single-channel atomic biomagnetometer and have used it to detect adult MCG signals. The magnetometer has sufficiently high sensitivity that it is fetal MCG capable. The next step is to develop a practical multi- channel, multidimensional, low-cost atomic magnetometer for fMCG. The specific aims are: 1. To improve the noise performance of our single channel vector magnetometer to 20 fT/ Hz over a 1-100 Hz bandwidth. 2. To further miniaturize it to a 10 cm diagonal size with integrated optics and electronics, and to design and fabricate a four-channel atomic biomagnetometer suit- able for fMCG studies. 3. To test and evaluate the technical performance of the biomagnetometer array using phantoms. 4. To integrate the biomagnetometer within a test system that is compatible with studies of pregnant women. 5. To make preliminary human subject measurements with the multichannel system. PUBLIC HEALTH RELEVANCE: Fetal magnetocardiography is an especially effective method for diagnosis of fetal arrhythmias. It can provide information that is not available through other technologies such as ultrasound. The proposed research into a new atomic magnetometer for fetal magnetocardiography has the potential to greatly reduce the cost and improve the performance of fetal magnetocardiography.